Acute flaccid paralysis and myelitis (AFP/M) in England
Data up to 2025 on acute flaccid paralysis and myelitis in England (AFP/M).
Applies to England
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Key points
Ten AFP/M cases not explained by a non-infectious cause were notified to UKHSA in England in 2025; 8 of which were in children under 15 years of age.
Historically, AFP/M reporting levels have been low, with potential under-ascertainment. Making AFP/M notifiable in 2025 was intended to increase the surveillance system’s sensitivity and improve ascertainment.
Background information
Since April 2025, under Schedule 1 of the Health Protection (Notification) Regulations 2010, cases of acute flaccid paralysis or acute flaccid myelitis (AFP/M), not explained by a non-infectious cause are notifiable in England.
Acute flaccid paralysis (AFP) is a rare but serious neurological illness which is normally due to inflammation of the spinal cord, known as acute flaccid myelitis (AFM). Clinically, it is characterised by rapid onset of weakness of an individual’s extremities, often including weakness of the muscles of respiration and swallowing, progressing to maximum severity within 10 days. The term ‘flaccid’ indicates weakness accompanied by hyporeflexia or areflexia in the affected limb or limbs.
In the past, AFP/M was most commonly caused by poliovirus infection. With the success of widespread vaccination programmes, polio has become very rare internationally. The UK has been certified polio-free by the World Health Organization (WHO) since 2003. AFP is now more often associated with other viral infections, particularly non-polio enteroviruses (NPEVs).
All AFP/M cases not explained by a non-infectious cause should be notified and appropriately investigated by clinicians to exclude polio. This is an essential component of polio surveillance and a requirement for the UK to maintain its polio elimination status. See how to report a case of acute flaccid paralysis or acute flaccid myelitis. The primary aim of AFP/M surveillance is to detect and investigate clinically compatible cases to exclude poliovirus infection. Surveillance also supports the identification of alternative infectious causes of AFP and improves understanding of the epidemiology of non-polio AFP cases. Making AFP/M a notifiable condition was intended to increase surveillance sensitivity and improve compliance with international standards for the Global Polio Eradication Initiative.